The mayor of the Polish city of Gdansk has been seriously injured after being stabbed on stage at the country’s biggest charity event, officials say.
Pawel Adamowicz, 53, had to be resuscitated after the attack and is in a critical condition in hospital.
The 27-year-old suspect, who has a criminal record, has been detained.
He reportedly shouted that he had been wrongfully imprisoned under the previous government, led by the mayor’s former party.
The incident took place at the finale of the annual Great Orchestra of Christmas Charity event, which was attended by hundreds of people.
The suspect, who was released from prison recently, had access to the scene using a media badge, Polish media say.
Television footage showed him shouting “Adamowicz is dead.”
The stabbing, during an event that raises money for children’s hospitals, has shocked Poland, the BBC’s Adam Easton in Warsaw reports.
Mr Adamowicz is a well-known political figure who has been mayor of Gdansk, a Baltic port city, for 20 years, our correspondent adds.
Moments before the attack, he posted a picture on his Instagram from the stage of the event, where dozens of people were holding white lights.
The popular mayor, a former member of Poland’s main opposition Civic Platform party, is seen as a liberal voice and has supported rights for minorities.
Interior Minister Joachim Brudzinski said the attack was “an act of inexplicable barbarism”.
Prime Minister Mateusz Morawiecki said on Twitter: “The attack on life and health of Paul Adamowicz is worthy of the highest condemnation.”
Also on Twitter, President Andrzej Duda said: “I pray for his return to health and full strength.“